This study demonstrates for the first time successful vascularization of solid porous matrices by means of an AV loop. Injection of osteogenic cells into axially prevascularized matrices may eventually create functional bioartificial bone tissues for reconstruction of large defects.

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Objectives: Lateral clavicle fractures have been reported following coracoclavicular (CC) ligament reconstruction with bone tunnels through the clavicle. Several techniques for CC reconstruction with different drill-hole measurements have been described. Our objective was to evaluate clavicle weakening related to tunnel diameters for common CC-reconstruction techniques. Methods: Testing was performed on 2 groups of 18 matched pair clavicles, which were randomly distributed between groups. There were no significant differences between the groups regarding bone mess density (BMD), clavicle width, age, and gender. One clavicle from each pair was prepared according to one of two reconstruction techniques; the contralateral clavicle was left intact. Both techniques placed 2 tunnels through the medial clavicle, 30 mm and 45 mm from the lateral border. Group 1 (mean age: 53, range: 44-63; mean BMD: 0.48, range: 0.39-0.59) was prepared with 2.4 mm tunnels and augmentation devices. Group 2 (mean age: 56, range: 45-63; mean BMD: 0.47, range 0.35-0.61) was prepared with 6.0 mm tunnels with hamstring grafts and tenodesis screws. A 3-point bending load was applied to the distal clavicles at 15 mm/min until failure. Ultimate failure load and anteriorposterior width 45 mm medial from the lateral border were recorded for each specimen. Strength reduction was determined as the percent reduction in ultimate failure load between paired intact and surgically prepared clavicles. Relative tunnel size was determined as the quotient of tunnel diameter and clavicle width. An independent observer performed all clavicle width measurements. Non-parametric statistics were used (MWU, Kendall's Tau). Results: The 6.0 mm technique significantly reduced clavicle strength relative to intact (p = 0.02) and caused significantly more strength reduction than the 2.4 mm technique (p = 0.02) (Figure). The 2.4 mm technique was not significantly different from intact. All but one fractures occurred at the medial tunnel. Clavicle width at the medial hole varied highly (mean: 18.1 mm, range: 12.3 -27.1 mm). There was a significant approximately linear correlation between clavicle width and strength reduction (p = 0.04, tau = -0.36) and between relative tunnel size and strength reduction (p < 0.01, tau = 0.51). Therefore, clavicle strength reductions of 30% and 50% relative to the intact state can be expected with relative tunnel diameters of 34.5% and 49.8% of the clavicle width, respectively. The intraobserver correlation coefficient of the width measurement was excellent (0.99; 95% CI: 0.98 -0.99). Conclusion: Coracoclavicular ligamentous reconstruction with 6.0 mm tunnels, graft, and tenodesis screws caused significantly greater decreases in the strength of the clavicle when compared to 2.4 mm tunnels with augementation devices and undrilled controls. Additionally, strength reductions correlated highly with the ratio of tunnel width relative to overall clavicle width. This information can help optimize techniques for reconstructing unstable distal clav...

Background:Several meta-analyses of randomized clinical trials have been performed to analyze whether double-row (DR) rotator cuff repair (RCR) provides superior clinical outcomes and structural healing compared to single-row (SR) repair. The purpose of this study was to sum up the results of meta-analysis comparing SR and DR repair with respect on clinical outcomes and re-tear rates.Methods:A literature search was undertaken to identify all meta-analyses dealing with randomized controlled trials comparing clinical und structural outcomes after SR versus DR RCR.Results:Eight meta-analyses met the eligibility criteria: two including Level I studies only, five including both Level I and Level II studies, and one including additional Level III studies. Four meta-analyses found no differences between SR and DR RCR for patient outcomes, whereas four favored DR RCR for tears greater than 3 cm. Two meta-analyses found no structural healing differences between SR and DR RCR, whereas six found DR repair to be superior for tears greater than 3 cm tears.Conclusion:No clinical differences are seen between single-row and double-row repair for small and medium rotator cuff tears after a short-term follow-up period with a higher re-tear rate following single-row repairs. There seems to be a trend to superior results with double-row repair in large to massive tear sizes.

Antegrade nailing of proximal humeral fractures using a straight nail can damage the bony insertion of the supraspinatus tendon and may lead to varus failure of the construct. In order to establish the ideal anatomical landmarks for insertion of the nail and their clinical relevance we analysed CT scans of bilateral proximal humeri in 200 patients (mean age 45.1 years (sd 19.6; 18 to 97) without humeral fractures. The entry point of the nail was defined by the point of intersection of the anteroposterior and lateral vertical axes with the cortex of the humeral head. The critical point was defined as the intersection of the sagittal axis with the medial limit of the insertion of the supraspinatus tendon on the greater tuberosity. The region of interest, i.e. the biggest entry hole that would not encroach on the insertion of the supraspinatus tendon, was calculated setting a 3 mm minimal distance from the critical point. This identified that 38.5% of the humeral heads were categorised as 'critical types', due to morphology in which the predicted offset of the entry point would encroach on the insertion of the supraspinatus tendon that may damage the tendon and reduce the stability of fixation. We therefore emphasise the need for 'fastidious' pre-operative planning to minimise this risk.

In later stages of vasculoangiogenesis a vascular network is going through a metamorphosis for optimal perfusion and economy of energy. In this study we make a quantitative approach to phenomena of remodelling in a bioartificial neovascular network and suggest variance of calibre as a parameter of neovascular maturation. For this study, 18 male Lewis rats were subjected to the AV loop operation in combination with a hard porous biogenic matrix and an isolation chamber. The animals were allocated into three groups for different explantation intervals set to 2, 4 and 8 weeks, respectively. Collective attributes like vascular density, percent fractional area and variance of calibre were evaluated for a predefined region of interest (ROI). Late morphogenesis was evaluated by means of scanning electron microscopy. After the fourth week the absolute number of vessels within the ROI decreased (P < 0.03) whereas, on the contrary, the fractional area of all segments increased (P < 0.02). The variance in calibre was significantly increased in the 8-week group (P < 0.05). Lymphatic growth after week 4, early pericyte migration as well as intussusceptive angiogenesis were identified immunohistologically. Phenomena of remodelling were evaluated quantitatively in a neovascular network and variance could be proposed as a parameter of net vascular maturation.

The augmentation of proximal humeral fracture fixation using a cancellous allograft might be a viable and reliable alternative to prevent early varus failure and to, moreover, lead to bony union in a non-compliant or high-risk patient population.